Morphological and Molecular Diversity, Phylogeography and Ethnobotany of Pnmus Il/ricana (Hook. f.) Kalkman in Ethiopia
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Date
2014-06
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Addis Ababa Universty
Abstract
This dissertation reports diversity, phylogeography and ethnobotany of Prunus
africana (Hook. f.) Kalkman in Ethiopia. P. africana is an economically important,
but endangered tree species of Africa. Five quantitative morphological traits were
studied in situ on 21 natural populations of P. aji'icana over its distribution range in
Ethiopia, and the following mean values were found: total height (l9.3m), bole height
(7.4m), diameter at breast height (70.2cm), bark thickness (20.3ulIn), and fresh bark
mass (I 59.6kg). Al"lOYA based ou the five traits revealed that there was significant
variation among populations (P < 0.001), which could be due to environmental andlor
genetic or age structure differences. Pearson's correlation analysis revealed significant
positive correlations among all traits (except bole height vs. bark thickness) (P <
0.0 I). Furthermore, all traits (except bark thickness) showed significant negative
correlations with altitude (P < 0.05). Six nSSRs and five cpSSRs were used to study
molecular genetic diversity and structure of the 21 P. aji'icana populations. A total of
89 nSSR and 14 cpSSR alleles, and 16 chloroplast haplotypes were found. The study
showed that P. [!!i'icana in Ethiopia maintains high levels of diversity in both nSSR
(Hr = 0.725) and cpSSRs (hI' = 0.703). AMOYA revealed that most (88.05%) of the
nuclear genetic variation occurs within populations; whereas nearly half (47.8%) of
chloroplast genetic variation occurs among populations. There was moderate nuclear
(FsT = 0.122) and high chloroplast (OST = 0.478) genetic differentiation among populations (P < 0.00 I). Distance-based clustering (peoA and UPGMA) and
individual-based population assignment methods as well as comparison of observed
and permuted differentiation indices revealed geographic pattern for nSSR diversity,
but no geographic pattern for cpSSR diversity, which could be due to differences in
the effect of genetic drift and/or the mechanism of gcne flow between cpDNA and
nDNA. However, Mantel test indicated signiticant positive correlation between
geographic and genetic distances for both nSSR (Rxy = 0.126) and cpSSR (Ib,:y =
0.107) (P = 0.00 I). The ethnobotanic study confirmed the multipurpose character of
P. {{fi'icana, and six major use categories (medicinal, construction and carpentry,
fuel/firewood, beverage preparation, apiculture, and traditional rituals) were
determined for the species. Significant genetic differentiation in more than 95% of the
population pairs suggests that almost all the populations deserve conservation, but as
there are often limitations of resources to conserve such a large number of
populations, prioritization may be needed. Thus, based on a weighted-score
population prioritization matrix that integrates genetic, morphological, conservation
status, and ethnobotanic criteria; Kuni, Jimma, and Assela are the top three priority
populations for conservation of the species.
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Keywords
Pnmus afrricana (Hook. f.) Kalkman in Ethiopia